def main():
    fish = 1
    while True:
        total,enough = fish,True
        for _ in range(5):
            if (total-1)%5 == 0:
                total = (total-1)//5*4
            else:
                enough = False
                break
        if enough:
            print(fish)
            break
        fish += 1
if __name__ == '__main__':
    main()
